Elon Musk is a South African-born U.S. engineer who founded of Tesla Motors, SpaceX and PayPal. He decided when he was in school that there were three important problems he wanted to pursue in life - the internet, clean energy and space exploration, particularly making life multi-planetary.

He appeared on
"The Daily Show" Tuesday evening (April 10), where he spoke with host
Jon Stewart about a rocket he invented and the challenges of colonizing Mars. Stewart points out that the four entities that have launched rockets into orbit are the U.S., China, Russia ... and Elon Musk.

"People often wonder how I went from internet payments to rockets ... I didn't expect that I would actually be doing them. The advent of the internet and particularly the sale of PayPal gave me the capital to start a rocket company and a car company," says Musk.

"The ultimate goal of SpaceX is to develop the technology necessary to make life multi-planetary. To enable a self-sustaining civilization on Mars," says Musk. "The moon's a small rock, but it's got no atmosphere, limited natural resources ... it's essentially impossible for us to travel to other star systems ... the next logical step is to make life multi-planetary. That will create a forcing function for improving space transportation technology."

And he says the reason they need to keep working towards these goals are two-fold.

"To ensure the continued existence of humanity ... the other reason is there have to be things that are exciting and inspiring," says Musk.

It's a fascinating interview and definitely worth watching both videos.